Statistical Analysis
We used SPSS statistical software for all analyses (IBM SPSS Statistics
for Macintosh, Version 20.0. Armonk, NY: IBM Corp.) with a two-sided P
value of less than 0.05 considered statistically significant. A
chi-squared test for association was conducted between MV disease (i.e.,
DMS or RMS) and each categorical/nominal variable; Fisher’s exact test
was used instead if a variable had any expected cell frequencies less
than 5. The Shapiro-Wilks test was used to assess the normality of
continuous variables. Independent groups of continuous variables were
compared using Student’s t-test if the variable had a normal
distribution or Mann-Whitney U test if the distribution failed to meet
this assumption. Mann-Whitney U tests were used to compare
MVACEQ of DMS and RMS while controlling for mean TMPG.
DMS patients were stratified based on MVACEQ (≤ 1.0
cm2, 1.0 to 1.5 cm2, >
1.5 cm2) to account for the small sample size, and a
Kruskal-Wallis test was used to identify echocardiographic variables
significantly impacted by MVACEQ stratification.
Echocardiographic variables were assessed using simple linear regression
analysis. A receiver operator characteristic (ROC) curve analysis was
created to determine the cutoff value of the DMSI value associated with
MVACEQ ≤ 1.5 cm2 and
MVACEQ ≤ 1.0 cm2. Cox proportional
hazards models were constructed to examine the prognostic determinants
of all-cause mortality in patients with DMS.